The equilibrium concentration of the diketone and enol tautomer of acetylacetone as a function of solvent is investigated by computational calculations. The percentage of enol at equilibrium is experimentally determined by NMR in varying solvents. An explicit solvent study was carried out combining an effective fragment potential with a polarized continuum. Previous work with water has shown agreement with NMR data, prompting expansion of the model to include more solvents. Approximately 400 initial random geometries are generated for acetylacetone with solvent molecules using a simulated annealing process sampling approximately 4 million structures. The lowest energy structures for each conformation were optimized at HF/6-31G(d) with a polarized continuum. The statistically significant geometries are optimized at M06-2X/6-311+G(d,p) with a polarized continuum to calculate the equilibrium concentration of acetylacetone. Explicit solvent molecules in conjunction with a polarized continuum were necessary to model the acetylacetone � solvent system in agreement with NMR data.

Keto-enol tautomerism of acetylacetone: Modeling solvation using effective fragment potential

245th National Meeting (2013)

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